Curable aryloxyphosphazene polymers

ABSTRACT

Polymers comprising randomly repeating units of the general formula ##STR1## wherein R 1  is linear or branched C 1  -C 10  alkoxy, R 2  is linear or branched C 1  -C 10  alkyl, hydrogen or halogen, and W is C 2  to C 10  alkenyl-substituted aryloxy. These novel polymers are elastomers and may be used to form flexible and semirigid foams and coatings. They display good fire retardance and low smoke levels.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 768,603, filed Feb. 14, 1977.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to elastomeric poly(aryloxyphosphazene) polymers,to flexible and rigid foams produced from said polymers and to a processfor preparing the polymers, foams and foam coatings. The polymers ofthis invention are soluble in tetrahydrofuran, benzene, anddimethylformamide, and exhibit excellent flame retardant andfoam-forming properties. Foams prepared from the polymers exhibitexcellent flame retardant properties and produce low smoke levels whenheated in an open flame. Foams prepared from such materials provideprotective coatings which are stable to heating.

2. Description of the Prior Art

The preparation of poly(aryloxyphosphazene) polymers has been disclosedin U.S. Pat. No. 3,856,712, Reynard et al; U.S. Pat. No. 3,856,713, Roseet al; and U.S. Pat. No. 3,883,451, Reynard et al. However, in contrastto the polymers of the present invention, the polymers described in thefirst-mentioned Reynard et al patent are copolymers that containselected quantities of both aryloxy and alkoxy side chains in thecopolymer backbone, whereas the polymers described in thelatter-mentioned Reynard et al patent are copolymers characterized bythe presence of halogen-substituted aryl side chains in the copolymerbackbone. The copolymers disclosed in the above-mentioned Rose et alpatent further differ from the polymers of the present invention sincethey are characterized by the presence of only alkyl-substituted aryloxyand unsubstituted aryloxy side chains.

Curable phosphazene polymers are disclosed in U.S. Pat. No. 3,888,799,Rose et al, and U.S. Pat. No. 3,702,833, Rose et al, where the curesites are unsaturated groups capable of crosslinking. However, these twopatents disclose copolymers having a high percentage of fluorine and aresignificantly different than the polymers disclosed herein. U.S. Pat.No. 3,948,820, Reynard et al, discloses curable phosphazene polymers inwhich the curing takes place by reaction of functional groups appendedto the phosphorus-nitrogen backbone. U.S. Pat. No. 3,994,838, Thompsonet al, discloses polyphosphazene foam vulcanizates in whichvulcanization results from crosslinking of an added unsaturatedmaterial, the polyphosphazene acting as a non-reactive additive.

Other related art may be found in U.S. Pat. Nos. 3,515,688; 3,700,629;3,702,833; and 3,856,712; but in each case, the polymers described inthese patents differ from the polymers of the present invention in theirstructure and physical characteristics.

SUMMARY OF THE INVENTION

The poly(aryloxyphosphazene) polymers of the present invention arecharacterized by the repeating unit

    -P=N-

which contain aryloxy-substituents on the phosphorus atoms in nonregularfashion and which can be more explicitly represented by the followingformulas: ##STR2## wherein R₁ is linear or branched C₁ -C₁₀ alkoxy, R₂is linear or branched C₁ -C₁₀ alkyl, hydrogen or halogen, and W is C₂ toC₁₀ alkenyl-substituted aryloxy.

It is to be understood that R₁ and R₂ are different and, as such, maycomprise phosphazene copolymers, terpolymers and the like. For example,where R₁ is alkoxy and R₂ is hydrogen, copolymers result. When R₂ ismixed, however, i.e. hydrogen and C₁ -C₁₀ linear or branched alkyl, thenterpolymers are produced. Various mixtures of R₁ and R₂ can be employedherein and such will give a copolymer having as many as 4 or morerepeating units, such randomly distributed on the phosphorus-nitrogenbackbone.

It is to be further understood that, in the copolymers of thisinvention, mixtures of different substituent radicals or mixtures ofdifferent ortho, meta and para isomers may also be present. Desirably,however, groups which sterically inhibit the reaction to produce theabove copolymers should be avoided. Absent the foregoing proviso, theselection of the various R₁ 's and R₂ 's will be apparent to anyoneskilled in the art based upon this disclosure and that of U.S. Pat.application Ser. No. 661,862, incorporated herein by reference. For thesake of simplicity, the copolymers of this invention which contain theaforesaid repeating units may be represented by the formula

    [NP(OC.sub.6 H.sub.4 -R.sub.1).sub.a (OC.sub.6 H.sub.4 -R.sub.2).sub.b (W).sub.c ].sub.n

wherein n is from about 20 to about 2,000 or more and wherein a or b,but not c, can be ≧O, and a + b + c = 2.

Examples of W are OC₆ H₄ CH=CH₂, OC₆ H₃ (R₃)CH=CH₂, OC₆ H₄ CH₂ CH=CH₂,OC₆ H₃ (R₃)CH₂ CH=CH₂, OC₆ H₃ (R₃)CH₂ CH=CH(R₄) and similar groups whichcontain unsaturation wherein R₃ and R₄ can be the same or different andare alkenyl, alkoxy, aryloxy, alkyl, aryl, and halogen. These groupsnormally react at temperatures of about 200°-350° F. However, ajudicious selection of different W permits multistage cures that may bedesirable from processing or end use considerations. It is also possibleto use as W in the above formulas monovalent radicals represented by theformula -OSi(OR⁴)₂ R⁵ and other similar radicals which contain one ormore reactive groups attached to the silicon atom. The introduction ofgroups such as W into phosphazene polymers is shown in U.S. Pat. Nos.3,888,799; 3,702,833; and 3,844,983, which are hereby incorporated byreference.

The above-described polymers may be crosslinked by the use ofconventional sulfur-type curing agents. Examples of sulfur-type curingsystems include vulcanizing agents such as sulfur, sulfur monochloride,selenium, tellurium, thiuram disulfides, p-quinone dioximes, polysulfidepolymers, and alkyl phenol sulfides. The above vulcanizing agents may beused in conjunction with accelerators, such as aldehyde amines,thiocarbamates, thiurams, guanidines and thiazole, as well asaccelerator activators, such as zinc oxide or fatty acids, e.g. stearicacid.

In the copolymers in accordance with the present invention, the ratio of(a + b):c affect the processability, smoke production, glass transitiontemperatures and a number of other properties of the copolymers. Theseratios also affect the copolymer's ability to be foamed and theproperties, such as rigidity, of the resulting foams. Accordingly, it iscontemplated that copolymers useful in forming the improved copolymersof this invention contain a mole ratio of a:b of at least 1:6 and up toabout 6:1, and preferably between 1:4 and 4:1. It is also contemplatedthat the mole ratio of c:(a+b) will be from 9:10 to 5:100, preferablyfrom 5:10 to 1:100, most preferably from 1:10 to 3:100.

The copolymers of this invention are prepared by a series of reactionsteps wherein the first step comprises thermally polymerizing a compoundhaving the formula (NPCl₂)₃ by heating such to a temperature and for alength of time ranging from about 200° C. for 48 hours to 300° C. for 30minutes, preferably in the absence of oxygen, and most preferably in thepresence of a vacuum of at least 10⁻¹ Torr. The product of such thermalpolymerization is a mixture of polymers having the formula (NPCl₂)_(n)wherein n ranges from about 20 to about 2,000.

The second step, the esterification step of this process, comprisestreating the mixtures resulting from the thermal polymerization with amixture of compounds having the formula

    M(OC.sub.6 H.sub.4 -R.sub.1).sub.x,

    M(OC.sub.6 H.sub.4 -R.sub.2).sub.x, and

    M(W).sub.x

wherein M is lithium, sodium, potassium, magnesium or calcium; x isequal to the valence of the metal M; and R₁, R₂ and W are as specifiedabove. The polymer (NPCl₂)_(n) is reacted with the mixture of metalcompounds as disclosed above, at a temperature and a length of timeranging from about 25° C. for 7 days to about 200° C. for 3 hours.Normally, the above esterification step is carried out in the presenceof a high boiling, substantially anhydrous solvent such as diglyme andthe like.

Polymers produced as a result of the esterification step are a mixtureof polymers having the formula [NP(OC₆ H₄ R₁)_(a) (OC₆ H₄ R₂)_(b)(W)_(c) ]_(n) wherein n, R₁, R₂, and W are as specified above andwherein a or b, but not c, can be ≧O and wherein a + b + c = 2, and thecorresponding metal chloride salt.

The polymeric reaction mixture resulting from this second, oresterification, step is then treated to remove the salt which resultsfrom the reaction of chlorine in the polymer mixture with the metal ofthe alkali or alkaline earth metal compounds. This is most readilyaccomplished by precipitating the salt and filtering the resultingmixture.

The copolymeric mixture formed from the esterification reaction can bepurified by fractionally precipitating the materials in order toseparate out the high molecular weight polymer from the low molecularweight polymer and any unreacted starting material. The fractionalprecipitation of the esterified polymeric mixture generally should becarried out at least twice, preferably at least four times, in order toremove as much of the low molecular weight polymeric from the polymermixture. In some cases, this fractional precipitation step may beeliminated, and the polymeric mixture from the esterification stepdirectly used in the coatings or foams in accordance with otherembodiments of the present invention.

The novel polymeric mixtures of this invention, as disclosed above, aresoluble in specific organic solvents, such as tetrahydrofuran, benzene,xylene, toluene, dimethylformamide, dimethylsulfoxide, and the like, andcan be easily cast into films from solutions by evaporation of thesolvent. These polymers are water resistant at room temperature and donot undergo hydrolysis at high temperatures. As such, the polymers maybe used to prepare films, fibers, coatings, molding compositions and thelike. They may be blended with such additives as antioxidants,ultraviolet light absorbers, lubricants, plasticizers, dyes, pigments,fillers such as litharge, magnesia, calcium carbonate, furnace black,alumina trihydrate, hydrated silicas, and other resins, withoutdetracting from the scope of the present invention.

Additionally, the blends may be used to prepare foamed products whichexhibit excellent fire retardance and which produce low smoke levels, oressentially no smoke when heated in an open flame. The foamed productsmay be prepared from filled or unfilled formulations using conventionalfoam techniques with chemical blowing agents, i.e. chemical compoundsstable at original room temperature which decompose or interact atelevated temperatures to provide a cellular foam. Suitable chemicalblowing agents include:

    ______________________________________                                                              Effective Temperature                                   Blowing Agent         Range ° C.                                       ______________________________________                                        Azobisisobutyronitrile                                                                              105-120                                                 Azo dicarbonamide (1,1-azobisformamide)                                                             100-200                                                 Benzenesulfonyl hydrazide                                                                           95-100                                                  N,N'-dinitroso-N,N'-dimethyl terephthal-                                      amide                 65-130                                                  Dinitrosopentamethylenetetramine                                                                    130-150                                                 Ammonium carbonate    58                                                      p,p'-oxybis-(benzenesulfonylhydrazide)                                                              100-200                                                 Diazo aminobenzene    84                                                      Urea-biuret mixture   90-140                                                  2,2'-azo-isobutyronitrile                                                                           90-140                                                  Azo hexahydrobenzonitrile                                                                           90-140                                                  Diisobutylene         103                                                     4,4'-diphenyl disulfonylazide                                                                       110-130                                                 ______________________________________                                    

Typical peroxide curable foam formulations include:

    ______________________________________                                        Phosphazene polymer       100 parts                                           ______________________________________                                        Filler (e.g., alumina trihydrate)                                                                       0-100   phr                                         Stabilizer (e.g., magnesium oxide)                                                                      2.5-10  phr                                         Processing aid (e.g., zinc stearate)                                                                    2.5-10  phr                                         Plasticizer resin (e.g., Cumar P-10,                                          coumarone indene resin)   0-50    phr                                         Blowing agent (e.g., 1,1'-azobisformamide)                                                              10-50   phr                                         Activator (e.g., oil-treated urea)                                                                      10-40   phr                                         Peroxide curing agent (e.g., 2,5-dimethyl-                                    2,5-di(t-butylperoxy)hexane)                                                                            2.5-10  phr                                         Peroxide curing agent (e.g., benzoyl                                          peroxide)                 2.5-10  phr                                         Cyclophosphazene plasticizer                                                                            0.1-100 phr                                         [e.g. N.sub.3 P.sub.3 (OC.sub.6 H.sub.5).sub.3 (OC.sub.6 H.sub.4 -4-OCH.su    b.3).sub.3                                                                    N.sub.3 P.sub.3 (OC.sub.6 H.sub.4 -4-OCH.sub.3).sub.3 (OC.sub.6 H.sub.4       -4-secC.sub.4 H.sub.9).sub.3 ]                                                                          0-100   phr                                         ______________________________________                                    

Typical sulfur curable formulations include:

    ______________________________________                                        Phosphazene polymer    100 parts                                              ______________________________________                                        Filler (e.g., alumina trihydrate)                                                                    0-250   phr                                            Stabilizer (e.g., magnesium oxide)                                                                   0-10    phr                                            Processing aid (e.g., zinc stearate)                                                                 2-20    phr                                            Blowing agent (e.g., 1,1'-azobisformamide)                                                           10-50   phr                                            Activator (e.g., oil-treated urea)                                                                   2-20    phr                                            Vulcanizer (sulfur)    0.5-5   phr                                            Pigment (TiO.sub.2)    0-10    phr                                            Accelerators                                                                   (e.g. zinc dimethyldithiocarbamate                                                                  0.4-5   phr                                             (e.g. tellurium diethyldithiocarbamate)                                                             0.2-2   phr                                             (e.g. N,N'-dibutylthiourea)                                                                         0.2-2   phr                                            Cyclophosphazene plasticizer                                                                         0.1-100 phr                                            ______________________________________                                    

While the above are preferred formulation guidelines, obviously some orall of the adjuvants may be omittted, replaced by other functionallyequivalent materials, or the proportions varied, within the skill of theart of the foam formulator.

In one suitable process, the foamable ingredients are blended togetherto form a homogeneous mass; for example, a homgeneous film or sheet canbe formed on a 2-roller mill, preferably with one roll at ambienttemperature and the other at moderately elevated temperature, forexample, 20°-40° F. The homogeneous foamable mass can then be heated, toprovide a foamed structure; for example, by using a mixture of a curingagent having a relatively low initiating temperature, such as benzoylperoxide, and a curing agent having a relatively high initiatingtemperature, such as 2,5-dimethyl-2,5-di-(t-butylperoxy) hexane, andpartially precuring in a closed mold for about 6-30 minutes at 200°-250°F., followed by free expansion for 30-60 minutes at 300°-350° F. In thealternative, the foaming may be accomplished by heating the foamablemass for 30-60 minutes at 300°-350° F. using a high temperature or lowtemperature curing agent, either singly or in combination. One benefitof utilizing the "partial precure" foaming technique is that an increasein the molecular weight of the foamable polymer prior to the foamingstep enables better control of pore size and pore uniformity in thefoaming step. The extent of "precure" desired is dependent upon theultimate foam characteristics desired. The desired foaming temperatureis dependent on the nature of the blowing agent and the crosslinkerspresent. The time of heating is dependent on the size and shape of themass being foamed. The resultant foams are generally light tan toyellowish in appearance, and vary from flexible to semirigid, dependingupon the relative amounts and the Young's modulus of the elastomeric andnonelastomeric polymers employed in the foam formulation. As indicated,inert, reinforcing or other fillers such as alumina trihydrate, hydratedsilicas or calcium carbonate can be added to the foams and the presenceof these and other conventional additives should in no way be construedas falling outside the scope of this invention.

Also, as mentioned above, the compositions of this invention can becrosslinked at moderate temperatures by conventional free radical and/orsulfur curing techniques when minor amounts of unsaturated groups W arepresent in the copolymer backbone. The ability of these compositions tobe cured at temperatures below about 350° F. makes them particularlyuseful as potting and encapsulation compounds, sealants, coatings andthe like. These materials are also useful for preparing crosslinkedfoams which exhibit significantly increased tensile strengths overuncured foams. These compositions are often crosslinked in the presenceof inert, reinforcing or other fillers and the presence of these andother conventional additives are deemed to be within the scope of thisinvention.

The following examples are set forth for purposes of illustration onlyand are not to be construed as limitations of the present inventionexcept as set forth in the appended claims. All parts and percentagesare by weight unless otherwise indicated.

EXAMPLE 1 Preparation of [NPCl₂ ]_(n)

250 parts of hexachlorocyclotriphosphazene, previously recrystallizedfrom n-heptane, were degassed and sealed in a suitable, thick-walledreaction vessel at 10⁻² Torr and heated to 250° C. for 10 hours.Polymerization was terminated when the contents of the vessel had justceased to flow when the vessel was inverted. Termination was effected bycooling the vessel to room temperature. The resulting polymeric mixturewas then dissolved in toluene to form an anhydrous solution.

EXAMPLE 2 Preparation of [NP(OC₆ H₄ -4-OCH₃).sub..985 (OC₆ H₄ -4-isoC₃H₇).sub..985 (OC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH).sub..03 ]_(n)

To the anhydrous toluene solution of poly(dichlorophosphazene) formed inExample 1, containing 3.72 equivalents of poly(dichlorophosphazene) wasadded an anhydrous diglyme-benzene solution of 1.83 equivalents of NaOC₆H₄ -4-OCH₃, 1.83 equivalents of NaOC₆ H₄ -4-isoC₃ H₇, and 0.15equivalents of NaOC₆ H₄ -2-OCH₃ -4-CH₂ CH═CH₂ at a temperature of 95°C., with constant stirring. After the addition, benzene was distilledfrom the reaction mixture until a temperature of 115°-116° C. wasattained. The reaction was then heated at reflux for 50-65 hours. At theend of this time, the terpolymer was precipitated by pouring thereaction mixture into a large excess of methyl alcohol. The polymer wasstirred in methyl alcohol for 24 hours. Next, it was added to a largeexcess of water and stirred for an additional 24 hours. The resultingproduct was produced in 43% yield. The product was soluble in benzene,toluene, tetrahydrofuran, and dimethyformamide. The terpolymer mixturewas cast from tetrahydrofuran. The film was flexible, did not burn, andwas water repellant.

EXAMPLE 3 Preparation of [NP(OC₆ H₄ -4-OCH₃).sub..97 (OC₆ H₄ -4-C₂H₅).sub..97 (OC₆ H₄ -2-CH₂ CH═CH₂).sub..06 ]_(n)

The anhydrous toluene solution of poly(dichlorophosphazene) formed inExample 1, containing 1.86 equivalents of poly(dichlorophosphazene), wasadded to an anhydrous diglyme-benzene solution of 0.90 equivalents ofNaOC₆ H₄ -4-OCH₃, 0.90 equivalents of NaOC₆ H₄ -4-C₂ H₅, and 0.084equivalents of NaOC₆ H₄ -2-CH₂ CH═CH₂ at a temperature of 95° C. withconstant stirring. After the addition, benzene was distilled from thereaction mixture until a temperature of 115°-116° C. was attained. Thereaction was then heated at reflux for 50-65 hours. At the end of thistime the terpolymer was precipitated by pouring the reaction mixtureinto an excess of methyl alcohol. The polymer was stirred in the methylalcohol for 24 hours. Next, it was added to a large excess of water andstirred for an additional 24 hours. The resulting product was anoff-white elastomer prepared in 51% yield. The terpolymer mixture wasthen cast to a tough, transparent film from solution in tetrahydrofuran.The film was flexible, did not burn, and was water repellant.

EXAMPLE 4 Preparation of [NP(OC₆ H₄ -4-OCH₃).sub..97 (OC₆ H₄ -4-secC₄H₉).sub..97 (OC₆ H₄ -2-CH₂ CH═CH₂).sub..06 ]_(n)

The procedure of Example 3 was followed, except that 1.84 equivalents ofpoly(dichlorophosphazene) were added to 0.89 equivalents of NaOC₆ H₄-4-OCH₃, 0.89 equivalents of NaOC₆ H₄ -4-secC₄ H₉, and 0.077 equivalentsof NaOC₆ H₄ -2-CH₂ CH═CH₂. The resulting product (33 percent yield) wasa tan elastomer. The terpolymer was soluble in benzene, tetrahydrofuranand dimethylformamide. The terpolymer mixture was then cast to aflexible film from a solution in tetrahydrofuran. The film did not burn,and was water repellant.

EXAMPLE 5 Preparation of [NP(OC₆ H₄ -4-OCH₃).sub..97 (OC₆ H₄-4-Cl).sub..97 (OC₆ H₄ -2-CH₂ CH═CH₂).sub..06 ]_(n)

The procedure of Example 3 was followed, except that 0.84 equivalents ofpoly(dichlorophosphazene) were added to 0.41 equivalents of NaOC₆ H₄-4-OCH₃, 0.41 equivalents of NaOC₆ H₄ -4-Cl, and 0.03 equivalents ofNaOC₆ H₄ -2-CH₃ CH═CH. The resulting product (41 percent yield) was acolorless plastic. The terpolymer was soluble in benzene,tetrahydrofuran and dimethylformamide. The terpolymer mixture was thencast to a flexible film from a solution in tetrahydrofuran. The film didnot burn, and was water repellant.

EXAMPLE 6 Preparation of [NP(OC₆ H₅).sub..64 (OC₆ H₄ -4-OCH₃).sub..64(OC₆ H₄ -4-t-C₄ H₉).sub..64 (OC₆ H₄ -2-OCH₃ -4-CH₂ CH═CH₂).sub..08 ]_(n)

The procedure of Example 3 was followed, except that 1.84 equivalents ofpoly(dichlorophosphazene) were added to 0.59 equivalents of NaOC₆ H₅,0.59 equivalents of NaOC₆ H₄ -4-OCH₃, 0.59 equivalents of NaOC₆ H₄-4-tert C₄ H₉, and 0.10 equivalents of NaOC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂.The resulting product (36 percent yield) was a colorless elastomer. Thetetrapolymer was soluble in benzene, tetrahydrofuran anddimethylformamide. The tetrapolymer mixture was then cast to a flexiblefilm from a solution in tetrahydrofuran. The film did not burn, and waswater repellant.

EXAMPLE 7 Preparation of [NP(OC₆ H₄ -4-O-nC₄ H₉).sub..90 (OC₆ H₄-4-tertC₄ H₉).sub..90 (OC₆ H₄ -2-CH₂ CH═CH₂).sub..10 ]_(n)

The procedure of Example 3 was followed except that 1.86 equivalents ofpoly(dichlorophosphazene) were added to 0.88 equivalents of NaOC₆ H₄-4-O-nC₄ H₉, 0.88 equivalents of NaOC₆ H₄ -4-tertC.sub. 4 H₉, and 0.13equivalents of NaOC₆ H₄ -2-CH₂ CH═CH₂. The resulting product (38 percentyield) was a colorless plastic. The terpolymer was soluble in benzene,tetrahydrofuran and dimethylformamide. The terpolymer mixture was thencast to a tough, flexible film from a solution in tetrahydrofuran. Thefilm did not burn, and was water repellant.

EXAMPLE 8 Preparation of [NP(OC₆ H₄ -4-OCH₃).sub..90 (OC₆ H₄ -4-C₂H₅).sub..90 (OC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂).sub..20 ]_(n)

The procedure of Example 3 was followed, except that 1.86 equivalents ofpoly(dichlorophosphazene) were added to 0.84 equivalents of NaOC₆ H₄-4-OCH₃, 0.84 equivalents of NaOC₆ H₄ -4-C₂ H₅, and 0.25 equivalents ofNaOC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂. The resulting product (43 percent yield)was a dark tan elastomer. The terpolymer was soluble in benzene,tetrahydrofuran and dimethylformamide. The terpolymer mixture was thencast to a rubbery film from a solution in tetrahydrofuran. The film didnot burn, and was water repellant.

EXAMPLE 9 Preparation of [NP(OC₆ H₄ -4-OCH₃)(OC₆ H₃ -2-OCH₃ -4-CH₂CH═CH₂)]_(n)

The procedure of Example 3 was followed, except that 1.86 equivalents ofpoly(dichlorophosphazene) were added to 1.11 equivalents of NaOC₆ H₄-4-OCH₃ and 1.11 equivalents of NaOC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂. Theresulting product (35 percent yield) was a colorless elastomer. Thecopolymer was soluble in benzene, tetrahydrofuran, anddimethylformamide. The terpolymer mixture was then cast to a flexiblefilm from a solution in tetrahydrofuran. The film did not burn, and waswater repellant.

In the preparation of curable phosphazene foams herein, the polymer andother ingredients were blended on a two-roll research mill with one rollat 120°-140° F. and the other at ambient conditions. The mixture wasmilled for at least 15 minutes to insure homogeneous blending. Theunexpanded blend was then precured in a press for one minute at atemperature of 200° F. and a pressure of 2000 psi. The pad was thencured at 180° F. for 120 minutes. The resultant material was freeexpanded in a circulating air oven for 20 minutes at 250° F. and 20minutes at 325° F.

The following Masterbatch formulation was used with the above procedureto prepare examples illustrative of sulfur-cured aryloxyphosphazenefoams:

    ______________________________________                                                              Parts by Weight                                         Polyphosphazene       100                                                     Alumina trihydrate    125                                                     1,1'-azobisformamide  20                                                      Oil-treated urea      5                                                       Zinc stearate         10                                                      Magnesium oxide dispersion                                                                          5                                                       Titanium dioxide      8                                                       Sulfur                2                                                       Zinc dimethyldithiocarbamate                                                                        1.5                                                     N,N'-dibutylthiourea  0.4                                                     Tellurium diethyldithiocarbamate                                                                    0.4                                                     ______________________________________                                    

EXAMPLE 10

Using the formulation and method above and with [NP(OC₆ H₄ -4-OCH₃)₀.97(OC₆ H₄ -4-C₂ H₅)₀.97 (OC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂)₀.06 ]_(n), thepolymer prepared in Example 3, a light tan, flexible foam was formed,Dm(corr) = 116; SV/g = 7. O.I. = 50.0. Density = 22.9 lb/ft³.

EXAMPLE 11

When 50 parts of phosphazene plasticizer, [NP(OC₆ H₄ -4-OCH₃)(OC₆ H₄-4-secC₄ H₉)]₃, was added to the ingredients in Example 10 and theresulting mix was foamed, a soft, flexible, resilient, light beige foamsponge was formed. Dm(corr) = 95. SV/g = 17. O.I. = 43.9. Density = 6.6lb/ft³.

EXAMPLE 12

Using the formulation and method above and with the polymer preparedaccording to Example 4, [NP(OC₆ H₄ -4-OCH₃)₀.97 (OC₆ H₄ -4-secC₄ H₉)₀.97(OC₆ H₄ -2-CH₂ CH═CH₂)₀.06 ]_(n), a flexible, fairly resilient, darkcream-colored foam pad was formed. Dm(corr) = 178. SV/g = 7. O.I. =43.5. Density = 68.7 lb/ft³.

EXAMPLE 13

Using the formulation and method above and with the polymer preparedaccording to Example 6, [NP(OC₆ H₅)₀.64 (OC₆ H₄ -4-OCH₃)₀.64 (OC₆ H₄-4-tC₄ H₉)₀.64 (OC₆ H₃ -2-OCH₃ -4-CH₂ CH═CH₂)₀.08 ]_(n), an expanded,light beige pad was formed. The foam was bendable, but stiff andsomewhat resilient. Dm(corr) = 84. SV/g = 10. O.I. = 42.5. Density = 9.2lb/ft³.

EXAMPLE 14

When 50 parts of phosphazene plasticizer, [NP(OC₆ H₄ -4-OCH₃)(OC₆ H₄-4-secC₄ H₉)]₃, was added to the ingredients in Example 13, and theresulting mix was foamed, an extremely well-expanded, very soft,flexible, light tan foam sponge was formed. Dm(corr) = 97. SV/g = 16.O.I. = 37.9. Density = 6.2 lb/ft³.

EXAMPLE 15

Using the formulation and method above and with the polymer preparedaccording to Example 8, [NP(OC₆ H₄ -4-OCH₃)₀.90 (OC₆ H₄ -4-C₂ H₅)₀.90(OC₆ H₄ -2-OCH₃ -4-CH₂ CH═CH₂)₀.20 ]_(n), a large, well-expanded, soft,resilient, flexible, pale brown foam sponge was formed. Dm(corr) = 51.SV/g = 8. O.I. = 38.3. Density = 7.4 lb/ft³.

EXAMPLE 16

Using the formulation and method above and with the polymer preparedaccording to Example 9, [NP(OC₆ H₄ -4-OCH₃)(OC₆ H₃ -2-OCH₃ -4-CH₂CH═CH₂)]_(n), a dense, fairly stiff, grayish-tan expanded pad wasobtained. Dm(corr) = 268. SV/g = 11. O.I. = 60.3. Density = 55.0 lb/ft³.

EXAMPLE 17

Using the formulation and method above and with 100 parts ofsulfur-curable, phosphazene polymer, [NP(OC₆ H₄ -4-OCH₃)₀.97 (OC₆ H₄-4-isoC₃ H₇)₀.97 (OC₆ H₄ -4-CH₂ CH═CH₂)₀.06 ]_(n), a well-expanded,flexible, somewhat resilient, pale cream-colored foam sponge was formed.Dm(corr) = 226. SV/g = 20. O.I. = 42.5. Density = 7.1 lb/ft³.

EXAMPLE 18

Using the formulation and method above and with 100 parts ofsulfur-curable phosphazene polymer, [NP(OC₆ H₄ -4-OC₄ H₉)₀.95 (OC₆ H₄-4-tC₄ H₉)₀.95 (OC₆ H₄ -2-CH₂ CH═CH₂)₀.10 ]_(n), a fairly stiff,non-resilient, grayish-brown expanded pad was formed. Dm(corr) = 168.SV/g = 8. O.I. = 43.3. Density = 50.3 lb/ft³.

What is claimed is:
 1. A process for foaming and curing a phosphazenecopolymer having randomly distributed repeating units represented by theformulas ##STR3## wherein R₁ is linear or branched C₁ to C₁₀ alkoxy, R₂is hydrogen, linear or branched C₁ -C₁₀ alkyl or halogen, and Wrepresents a monovalent radical containing a group capable of acrosslinking chemical reaction at moderate temperatures, said groupbeing attached to a P atom by a -O- linkage, which process comprisesmixing said phosphazene copolymer with a chemical blowing agent and asulfur-type curing agent and heating the resulting mixture to atemperature sufficient to decompose said blowing agent and cure thecopolymer.
 2. The process of claim 1 wherein said blowing agent is1,1'-bisazoformamide.
 3. A process for foaming and curingpoly(aryloxyphosphazene) copolymers having the general formula:

    [NP(OC.sub.6 H.sub.4 -R.sub.1).sub.a (OC.sub.6 H.sub.4 -R.sub.2).sub.b (W).sub.c ].sub.n

wherein R₁ is C₁ -C₁₀ linear or branched alkoxy; R₂ is hydrogen, C₁ -C₁₀linear or branched alkyl or halogen; W represents a monovalent radicalcontaining a group capable of a crosslinking chemical reaction atmoderate temperatures, said group being attached to a P atom by a -O-linkage; n is from 20 to 2000, a or b but not c O, and a+b+c=2, theratio of a:b is from about 1:6 to 6:1, and the ratio of c:(a+b) is 9:10to 5:100, which process comprises mixing said phosphazene copolymer witha chemical blowing agent and a sulfur-type curing agent and heating theresulting mixture to a temperature sufficient to decompose said blowingagent and curing the copolymers.
 4. A phosphazene copolymer foamproduced by the process of claim 1.